The present invention is related to a probe for a scanning type microscope which obtain substance information from a surface of a specimen by using a nanotube as a probe needle, saying in more detail, being related to a cantilever for a high quality scanning type microscope and a probe for a high quality scanning type microscope using the cantilever, which can obtain substance information from a surface of a specimen, and in which a nanotube probe needle is disposed substantially vertically against the surface of a specimen.
In order to image a surface structure of a specimen by an atomic force microscope abbreviated as AFM, a probe needle needed which is caused to contact with the surface of the specimen and obtains signals. In the past, as this probe needle, a silicon cantilever was known, which possesses a protruding portion with a sharp tip end such as a pyramid or a cone (called pyramidal portion).
In recent year, a carbon nanotube has been discovered as a carbon matter having a new structure. The carbon nanotube is from about 1 nm to several 10 nm in diameter and several xcexcm in length, and its aspect ratio is around 100-1000. It is difficult to form a probe needle of 1 nm diameter by means of the present of semiconductor technique. Therefore, in this respect, the carbon nanotube provides best condition for the probe needle for the AFM.
In such a situation, H. Dai and others published, in the Nature magazine (Vol.384, Nov. 14, 1996), a report with respect to the AMF probe in which a carbon nanotube is stuck on the tip end of the protruding portion of a cantilever. Though the probe proposed by them was of epoch-making, the carbon nanotube fell off from the protruding portion during repeatedly scanning surfaces of specimens, since the carbon nanotube was simply stuck on the protruding portion.
In order to solve this weak point, the present inventors have achieved to develop a method fastening firmly the carbon nanotube to the protruding portion of the cantilever. Results of this invention have been published; the first fastening method is disclosed in Japanese Patent Application Laid-Open (Kokai) No. 2000-227435, and the second fastening method is disclosed in Japanese Patent Application Laid-Open (Kokai) No. 2000-249712.
The fist fastening method above-mentioned is that a coating film is formed by means of irradiating an electron beam to the base end portion of a nanotube, and next the nanotube is fastened to the cantilever by means of coating the nanotube with the coating film. The second method is that the base end portion of the nanotube is fusion-fastened to the protruding portion of the cantilever by means of irradiating an electron beam on the base end portion of the nanotube or by means of flowing current.
However, the resolution of detection of signals is often reduced according to a disposition of a nanotube, even if the nanotube is fastened to the protruding portion of a conical form cantilever.
FIG. 14 shows a stereo-structure diagram of a probe of a conventional scanning type microscope. The probe 20 of the scanning type microscope comprises a cantilever 2 and a nanotube 12. This cantilever 2 comprises a cantilever portion 4, its fastening rear portion 6 and a protruding portion 8 (called pyramid portion) of the forward end, and the protruding portion 8 possesses a sharp tip end 8a which serves as a probe needle. Though a base end portion of the nanotube 12 is fastened to the protruding portion, it is, in many cases, not fastened, passing the tip end 8a as shown in the diagram, since a high technique is needed in order to fasten so as to pass the tip end 8a. 
In scanning a specimen surface 24 of a specimen 22 by means of this probe 20, the nanotube tip end 18 and the tip end 8a of the protruding portion both act as probe needles. In a surface image obtained by this probe, the image obtained by the tip end 18 of the nanotube and the image obtained by the tip end 8 of the protruding portion both overlap with each other, so that the degree of sharpness of the image itself is caused to reduce.
FIG. 15 is a stereo-structure diagram of another conventional scanning type microscope. In this conventional example, the action of the tip end 8a of a protruding portion as a probe needle is blocked, since a nanotube 12 passes the tip end 8a of protruding portion.
However, when this nanotube tip end 18 is caused to contact with the specimen surface 24, the nanotube 12 is not orthogonal, but is oblique with an oblique anglexcfx86 against a mean surface 26 of the specimen surface 22. The nanotube tip end 18 can not follow sharp indentations and projections of the specimen surface 24 in oblique states, so that non-detected black regions a That is, also in this case, the reduction of detection resolution is inevitable.
These weak points are caused by the reason that the conventional protruding portion 8 of the cantilever is formed in a pyramidal fashion, so that the protruding portion necessarily possesses the sharp tip end 8a. In other ward, if the conventional probe needle for the AFM is used in intact state, these weak points come out.
Accordingly, an object of the present invention is to realize a probe for a vertical scanning type microscope, in which a protruding portion of a cantilever does not possess a sharp tip end and furthermore, during detection, a nanotube tip end substantially perpendicularly abuts against a specimen surface.
The present invention provides, in a probe for a scanning type microscope which obtains substance information of a specimen surface by means of a tip end of a nanotube probe needle fastened to a cantilever; a cantilever for a vertical scanning type microscope characterized in that a fixing region, to which a base end portion of a nanotube is fastened, is provided in a cantilever, and the fixing region is set so that height direction of the above described fixing region is kept perpendicular against a specimen surface when the cantilever is set in a measuring state for the specimen surface.
The present invention provides the cantilever for a vertical scanning type microscope described in the first part of the present invention in which the above described fixing region is a fixing plane.
The present invention provides a fixing hole of the above described fixing region, into which the base end portion of the nanotube is inserted, and a cantilever for the vertical scanning type microscope described in the first part of the present invention, in which the axis direction of the fixing hole accords with the height direction above described.
The present invention provides the cantilever for the vertical scanning type microscope described in the first part of the present invention, wherein the above described fixing region is a fixing gap to which the base end portion of the nanotube is inserted to fit and the gap direction of this fixing gap accords with the height direction above described.
The present invention provides the cantilever for the vertical scanning type microscope described in the first part of the present invention, in which the above described fixing region is an edge line portion and the direction of this edge line accords with the height direction above described.
The present invention provides the cantilever for the vertical scanning type microscope described in the first part of the present invention, wherein the above described fixing region is a fixing curved-surface and the cantilever is settled so that and the height direction of a tangent plane of the fixing curved surface above described is perpendicular against a specimen surface, when the cantilever is set in measuring state.
The present invention provides the cantilever for the vertical scanning type microscope described in the first part of the present invention, by which the above described fixing region is formed by utilizing focused-ion-beam process, etching process, or deposition process.
The preset invention provides, in a probe for the vertical scanning type microscope which obtains substance information of a surface of specimen by a tip end of a nanotube probe needle fastened to the cantilever; the probe for the vertical scanning type microscope characterized in that a fixing region, to which a base end portion of a nanotube is fastened, is provided in the cantilever, and the fixing region is set so that height of direction of the above described fixing region is kept perpendicular against a surface of specimen, when the cantilever is set in a measuring state for the surface of a specimen, and the base end portion of the nanotube is fastened in the height direction of this fixing region.
The present invention provides the probe for the vertical scanning type microscope described in the eighth part of the present invention, wherein the axis line of the above described nanotube is at an angle of about (xcex8+90) degrees with an axis direction of the cantilever portion, when the axis direction of the cantilever portion of the above described cantilever is set in measuring state, in a backward rising fashion, at the angle xcex8 against a surface of a specimen.